In the last few years, several antenna designs of rectenna that meet various objectives have been proposed for use in RF energy harvesting. Among various antennas, microstrip patch antennas are widely used because of their low profile, light weight, and planar structure. Conventional patch antennas are rectangular or circular in shape, but variations in their basic design are made for different purposes. This paper begins with an explanation and discussion of different designs, put forward with an aim of miniaturization, harmonic rejection, and reconfigurability. Finally, microstrip patch structured rectennas are evaluated and compared with an emphasis on the various methods adopted to obtain a compact rectenna, harmonic rejection functionality, and frequency and polarization selectivity.
In wireless sensor networks (WSN) systems, various indoor environmental parameters can be monitored in real time by an RF wireless sensor module. A wireless sensor module with several sensors is developed for an indoor environment monitoring system. ZigBee is a wireless standard for personal area network (PAN) sensor monitoring and control, also known as IEEE 802.15.4. In this paper, we designed a wireless sensor module that had a ZigBee communication module and a sensor module for monitoring a room or an office environment using WSN. The sensor module has various enlargements for various types of sensors, for example, a humidity sensor, temperature sensor, and O 2 and CO 2 sensors. Using ZigBee technology of 2.4 GHz Industrial, Scientific, and Medical (ISM) band, we could monitor the information from terminal PC modules that are attached to the wall of an office or a room. A wireless sensor device was developed to circuit schematic using PowerPCB tool PADS and made it a printed circuit board (PCB). From the results of our tests, we confirmed that the designed wireless sensor module and room monitoring system can supply a comfortable environment for people by monitoring the indoor environment.
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